Wet Spring Favors Tick Survival

Wet Spring Favors Tick Survival

May 25, 2007

A wet spring brings perfect conditions for ticks and the diseases they carry, University of Nebraska-Lincoln entomologists say. Three tick species — the Rocky Mountain wood tick, the American dog tick and the brown dog tick — are the most common ticks found in Nebraska, said Jack Campbell, entomologist at UNL's West Central Research and Extension Center at North Platte.

The Rocky Mountain wood tick and the America dog tick can transmit Rocky Mountain spotted fever. Symptoms of Rocky Mountain spotted fever include severe headaches, chills, fever and general aches and pains, Campbell said.

"A reddish-purple-black rash also may occur on the bottoms of the feet, ankles, palms, wrists and forearms a few days after infection," the Institute of Agriculture and Natural Resources specialist said. "The rash can spread to the trunk, neck and face if left untreated. In addition, those infected can become highly agitated, develop insomnia, become delirious or go into a coma."

Diagnosis for Rocky Mountain spotted fever can be confirmed with a blood test by a local physician, Campbell said. Antibiotics can control the disease.

Another well-known disease, Lyme disease, also is transmitted by ticks; however, the deer or black-legged tick, which is the Lyme disease carrier, is not found in Nebraska, Campbell said.

The brown dog tick, which is found in Nebraska, is capable of transmitting several canine diseases, said David Boxler, UNL entomology research technician.

To combat ticks, the entomologists recommend controlling tick-infested vegetation around the home and using a contact residual insecticide such as Sevin on fringe areas of yards.

"This can reduce tick infestation of children, adults and pets," Campbell said.

Insect repellents for humans and shampoos or collars containing an insecticide for pets can help control tick infestations. People spending time in tick-infested areas should thoroughly examine their bodies after leaving the area, Boxler said.Tight-fitting clothing around the wrists, neck, waist and ankles also reduces the chance of ticks attaching. Light-colored clothing makes ticks easier to see.

To remove ticks, use tweezers to grasp the tick at the point where mouth parts enter the skin and gently pull until the tick is removed.

"Ticks generally require several hours of attachment before they can transmit a disease," he said. "Adult ticks climb on vegetation in the spring along animal trails or forested areas and attach to passing animals, most commonly horses or cows. This behavior is called questing. When the tick attaches to the animal it cuts a hole in the skin and inserts its feeding tube."

These feeding tubes have rows of recurved barbs that anchor the tick to its host. The tick then inserts an anticoagulant, which prevents blood from clotting and allows the tick to feed for a long time, he said.

The life cycle of ticks consists of four stages: eggs, six-legged larva (seed ticks), eight-legged nymph and adult.These three tick species are all three-host ticks. Three-host ticks feed on blood, as seed ticks drop off the animal, reattach later as a nymph to a larger animal, drop off and reattach to an even larger animal, usually cattle or horses (or humans). The brown dog usually attaches to dogs for all three phases.

The survival rate for seed ticks, nymphs and adults usually is low because of the environment and the difficulty of finding a host. However, the low survival rate is offset by the great number of eggs deposited by a female and the ability of all life stages to survive long periods without feeding.

For more detailed information on ticks, consult Nebraska Extension NebGuide G1220, Controlling Ticks, available online or from local extension offices. More information also is available at UNL's Department of Entomology Web site.

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